Sinus Tachycardia – Learning the Beat

Ever wonder why your heart beats? The human heart has its own electrical impulse that triggers heart muscles to contract and pump blood in a correct sequence. If the electrical signal is interrupted or goes erratic, abnormal cardiac rhythms or beats arises which can consequently lead to ineffective heart functioning.

The heart beat is one indicator of good circulation and cardiac function. If your heart beats too slow or too fast, the distribution of blood and oxygen in your body will be greatly affected. This is why nurses always check your pulse and hook you to an electrocardiograph monitor – to keep a close watch of your cardiac rhythm!

A variety of factors can affect the beating of the heart and one of the most common cardiac rhythms is sinus tachycardia.

What is Sinus Tachycardia?
It is a condition in which the sinoatrial (SA) node rate frequency is greater than 100 beats per minute (bpm) in normal adults. The term “sinus” comes from sinoatrial, “tachy” generally means more or greater and “cardia” or heart.

So how do the electrical impulses work? The heart’s impulses originate from its base, specifically at the SA node. It is also often termed as the pacemaker. The SA node is in charge of the heart rate, which is normally 60 – 100 bpm in adults. From the SA node, it travels to the atrioventricular (AV) node going to the Bundle of His and lastly to enervate the Purkinje fibers.

With sinus tachycardia, the heart literally beats faster. This may or may not produce other symptoms thus it is important to know the activities that can precipitate the condition.

What Are the Causes of Sinus Tachycardia?
The most common factors that cause sinus tachy are physical activity and conditions wherein catecholamine release is enhanced in response to flight, fright, anger, and/or stress. Here are other factors that may affect cardiac rhythm:

Physiological : Why does your heart beat like a drum when you are scared or excited about something? This is your body’s way of preparing you – filling you up with the needed energy and oxygen – just in case you will need to bolt out of the room in a flash. These emotional changes like anxiety, excitement, fear and anger can greatly influence your heart’s rhythm so better keep your feelings in check.
Other activities also affect heart rate such as postural changes, exercise, food digestion and pregnancy. With pregnancy, the mother’s heart beats faster in order to provide for the fast growing fetus in her womb.
You also notice that your beats are more rapid after you’ve eaten. This is so food can be broken down and distributed to your body. Added to that, age is also a big factor and it should be noted that children have faster heart rates as compared to adults.

Drug or substance-induced : Sympathomimetic (adrenergic) drugs like ephedrine, epinephrine and other medications that contain these catecholamine substances can increase your heart rate. Parasympathetic blocking (anticholinergic) drugs such as atropine can also cause tachycardia.
Check the medication labels. Sometimes, cough medications contain epinephrine thus the reason for your palpitations whenever you take them. Coffee and other caffeine-containing food and beverages also contribute to sinus tachycardia. In addition, cigarette or tobacco is one great factor so you should think twice about having one with your coffee.

Disease-caused : Systemic diseases like high fever, anemia, infections, endocrine problems (hyperthyroidism, pheochromocytoma and others), pain, and others can cause your heart to beat faster. When you fall ill, your body needs more energy and oxygen in order to fight off the disease and also to sustain the normal organ functioning.

Cardiovascular problems : Conditions that decrease the circulating blood volume such as – hemorrhage or acute blood loss, hypotension, dehydration and shock gravely increases the heart rate. In order to compensate for the loss and continue providing blood to the vital organs, the heart must pump faster.
More serious heart conditions such as heart failure, cardiomyopathy, heart infections, acute myocardial infarction (heart attack) can also result in a fast rhythm.

Respiratory problems : Problems with breathing and respiration also cause the cardiac rate to increase in the same way as cardiac conditions. Chronic pulmonary diseases and hypoxia (decrease oxygen in tissues) trigger heart to work harder to cover for the inadequacies.

What are the Symptoms of Sinus Tachycardia?
Sinus tachy is often asymptomatic; but as it progresses, you may also experience the following:

Heart rate more than 100 bpm

Palpitations

Sweating

Dizziness leading to vertigo

Fatigue

Other abnormal heart rhythms (arrhythmia) may also be present

Chest pain (angina)

How is Sinus Tachycardia Diagnosed?
If you have a heart rate greater than 100 bpm with accompanying symptoms, you should submit yourself for an Electrocardiogram (ECG) examination. Your ECG result should exhibit:

Normal p wave morphology

P-R interval greater than 0.12 seconds

Frequency of >100 times/min

What is the Management for Sinus Tachycardia?
If it is caused by physiologic or substance-induced factors, there is no need for special treatment. If you had a stressful activity, take some rest and avoid stimulating food and beverages like caffeine.

If your tachycardia results from a disease, whether cardiac, respiratory or systemic, treatment must be directed to these underlying causes.

Heart related factors must be attended to immediately as the tachycardia might be a signal to an impending doom! The drug of choice to reign in the galloping rhythm is beta blockers such as metoprolol.

For patients who have persistent symptoms, more aggressive treatment may be attempted such as radiofrequency catheter ablation.

How Can Sinus Tachycardia be Prevented?
Prevention is directed towards the causes so you should incorporate the following in your lifestyle:

Avoidance of stimulating foods and drinks that contain caffeine. You should also keep away from strong tea, alcohol and cigarettes.